Shoe sole construction with wave cushion

ABSTRACT

Implementations disclosed herein provide for shoes including one or more wave cushions that provide temporary storage of the shoes’ impact energy with the ground and return of a portion of that energy to enhance a runner’s running economy. The wave cushions may include a pair of foundation layers, each with an engagement surface and a sinusoidal sectional profile. The sinusoidal sectional profiles are phase offset, and the elastic membrane is oriented between the engagement surfaces. The engagement surfaces together act as alternating matched pairs of actuators and cavities. Each actuator stretches a portion of the elastic membrane into a cavity when a runner’s weight is applied, converting the runner’s kinetic energy to potential energy stored in the stretched and deformed elastic membrane. As the runner’s weight is removed, the elastic membrane springs back into a substantially planar orientation, transferring the stored potential energy back to the runner as kinetic energy.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of priority to U.S. Provisional Pat. Application No. 63/265,976 entitled “Shoe Sole Construction With Wave Cushion” and filed on Dec. 23, 2021, which is specifically incorporated by reference herein for all that it discloses or teaches.

BACKGROUND

Maintaining proper alignment and stability while running are important factors in reducing the risk of injury to a runner. Many athletic shoes are designed to cushion the runner’s foot and to help absorb impact when the runner’s feet contact the ground. However, by damping the shock of impact using traditional materials such as ethylene vinyl acetate (EVA) foam, a substantial portion of the kinetic energy is dissipated as heat rather than temporarily stored and subsequently returned the runner. A shoe capable of more efficiently receiving, storing, and returning to the runner the kinetic energy of the runner’s periodic ground contact increases running economy and may also encourage an efficient running form for the runner.

SUMMARY

Implementations disclosed herein provide for shoes including one or more wave cushions that provide the aforementioned temporary storage of the shoes’ impact energy with the ground and return of a portion of that energy (e.g., at least 50% of the impact energy) to enhance the runner’s running economy. The wave cushions may include a first foundation layer with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer and the second foundation layer and releases kinetic energy by expanding the first foundation layer away from the second foundation layer.

Other implementations are also described and recited herein.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 illustrates an example shoe having a sole construction including a wave cushion.

FIG. 2 illustrates an example sole construction including a wave cushion under a progressively increasing compressive load.

FIG. 3A illustrates an example shoe having a sole construction including a full-length wave cushion.

FIG. 3B illustrates an example shoe having a sole construction including localized wave cushions.

FIGS. 4A-4C illustrate example wave cushions with varying frequencies and amplitudes.

FIGS. 5A and 5B illustrate flexure of an example wave cushion.

FIG. 6A illustrates a perspective view of an example foundation layer of a wave cushion with an engagement surface wave profile running exclusively in the y-direction.

FIG. 6B illustrates a perspective view of an example foundation layer wave cushion with an engagement surface wave profile running in both the x-direction and the y-direction.

FIGS. 7A-7C illustrate example wave cushions with varying locking arrangements.

FIG. 8 illustrates an example wave cushion configured as a pre-assembled cassette to be installed into a sole construction cavity.

FIG. 9 illustrates a sectional view of another example sole construction including a wave cushion.

FIG. 10 illustrates a partial perspective view of another example sole construction including a wave cushion.

FIG. 11 illustrates example operations for providing elastic energy return to a user during an impact event with a ground surface.

DETAILED DESCRIPTIONS OF THE DRAWINGS

A “natural running” form can help to reduce the frequency and severity of some common running injuries. “Natural running” refers to a form of running that a habitually barefoot runner adopts to reduce loading rates and protect their feet from excessive impact energy with the ground while moving quickly and efficiently. A runner practicing a natural running form strikes the ground with their feet close to a point under the runner’s center of gravity with relaxed feet rather than over striding (i.e., striking the ground with the runner’s feet in front of the runner’s center of gravity) with an aggressively dorsiflexed ankle. Using an efficient natural running gait, the runner lands lightly with a relaxed foot and avoids exaggerated joint positions and excessive use of muscular force.

Traditional walking and running shoes cushion the runner’s feet and help to absorb impact energy when the runner’s feet contact the ground. However, traditional materials such as EVA foam dampen the shock of impact by dissipating kinetic energy as heat, which renders the kinetic energy not reusable by the runner. Some of this energy can be effectively “stored and returned” to the runner if it is converted to potential energy, temporarily stored in the runner’s shoes, and returned to the runner’s feet when the runner pushes off the ground. Shoes capable of storing and returning ground impact energy to the runner reduces energy conversion to heat, and consequently improve running economy.

Such shoes may also encourage more efficient running forms, such as natural running. Some runners who are learning natural running form have difficulty not over striding the ground. A running shoe that stores and returns energy helps to mitigate over striding by reducing interference with the runner’s gait cycle. Such shoes may further promote speed and efficiency by providing for more energy return when the runner utilizes a natural running form. In other implementations, implementations disclosed herein may be utilized for providing energy return to runners utilizing a heel-strike leading gait cycle.

Implementations disclosed herein provide for shoes including one or more wave cushions that provide the aforementioned temporary storage of the shoes’ impact energy with the ground and return of a portion of that energy (e.g., at least 50% of the impact energy) to enhance the runner’s running economy. The wave cushions may include a first foundation layer with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer and the second foundation layer and releases kinetic energy by expanding the first foundation layer away from the second foundation layer.

The first engagement surface and the second engagement surface together act as alternating matched pairs of actuators and cavities. Each actuator stretches a portion of the elastic membrane into a cavity when a runner’s weight is applied to a top side (e.g., a foot-facing side) of the first foundation layer, converting the runner’s kinetic energy to potential energy stored in the stretched and deformed elastic membrane. As the runner’s weight is removed from the first foundation layer, the elastic membrane springs back into a substantially planar orientation, transferring the stored potential energy back to the runner as kinetic energy. As compared to prior art solutions that may also utilize deformation of an elastic membrane to convert kinetic energy to potential energy, the presently disclosed technology stretches and deforms most or all of the elastic membrane to store energy. Further, the presently disclosed technology stretches and deforms the elastic membrane in a manner that smoothly transitions between a substantially planar elastic membrane in an unloaded state and a substantially sinusoidal elastic membrane in a fully loaded state.

The described technology may also be useful for purposes other than running. For example, while runners are specifically described as using shoes disclosed herein, the described technology may similarly be used by other users of footwear that are not necessarily runners or using the shoes described herein for running. Further, the described technology may also be useful for providing energy storage and return (or release) to areas of a user’s body other than their feet, such as their hands. Thus, this technology is also contemplated for use in gloves and other active wear for use during physical activities (e.g., running, and biking) when energy storage and return is desired.

FIG. 1 illustrates an example shoe 100 having a sole construction 102 including a wave cushion 104. The sole construction 102 is generally attached to an upper 114 to form the overall shoe 100. The upper 114 is generally made of fabric or other materials to form a top portion of the shoe 100 that surrounds and encloses a runner’s foot. The upper 114 is attached to the sole construction 102, which underlies and contacts the runner’s foot when the foot is in the shoe 100. The upper 114 may be attached to the sole construction 102 in a variety of ways such as via stitching, adhesives, etc.

The sole construction 102 includes a cushioning and support layer 116 (also referred to herein as a midsole) including an upper surface (e.g., a foot-facing surface) that is sized and shaped to receive and substantially underlie the runner’s foot, thereby cushioning and supporting the runner’s foot. The cushioning and support layer 116 may be composed of a variety of materials such as ethylene vinyl acetate (EVA), polyurethane (PU), or other foam or soft, pliable materials. In other implementations, an elastomeric viscous foam, gel, or other flexible framework, or combination of materials may be used. The cushioning and support layer 116 further includes a lower surface (e.g., a ground-facing surface), and in some cases a cavity, that secures the wave cushion 104 within the sole construction 102.

An abrasive-resistant underlayer 118 (or ground engagement layer) is attached to a lower surface of one or both of the wave cushion 104 and the cushioning and support layer 116 and is configured to contact the ground when the shoe 100 is in use. For example, the abrasive-resistant underlayer 118 may be attached directly to the wave cushion 104, but in areas of the sole construction 102 where the wave cushion 104 to is not present, the abrasive-resistant underlayer 118 may be attached directly to the cushioning and support layer 116. As the wave cushion 104 functions independently of the abrasive-resistant underlayer 118, it can be applied to virtually any style shoe with any style abrasive-resistant underlayer 118. In some implementations, the wave cushion 104 itself may function as the abrasive-resistant underlayer, depending on materials selection for the wave cushion 104 (e.g., the second foundation layer 122, discussed below, may be molded with lugs or other ground-engaging features on a ground-facing surface of the second foundation layer 122). Other implementations may omit one or more layers or include layers in addition to or in lieu of the upper 114 and the sole construction 102, and the various sublayers thereof.

A portion of the sole construction 102 is shown transparent in FIG. 1 to illustrate the wave cushion 104. In practice, the wave cushion 104 may be fully enveloped by the sole construction 102 and thus not visible from the exterior of the shoe 100 or the wave cushion 104 may extend to the inside and/or outside extents of the sides of the shoe 100, and thus visible in a similar manner to that depicted in FIG. 1 . Still further, the wave cushion 104 may be fully enveloped by the sole construction 102, but the sole construction 102 material on the inside and/or outside extents of the sides of the shoe 100 may be transparent, translucent or non-existent, thus rendering the wave cushion 104 partially or fully visible in a similar manner to that depicted in FIG. 1 .

The sole construction 102 includes a hindfoot or heel region 106, a midfoot region 108, a forefoot region 110, and a toe region 112. The heel region 106 generally underlies or substantially underlies the length and width of a heel of the runner’s foot. The midfoot region 108 is positioned forward or anterior to the heel region 106 and underlies or substantially underlies the arch or “middle” region of the runner’s foot, which typically includes the region underlying the navicular, cuboid, and cuneiform bones of the runner’s foot. The forefoot region 110 is positioned forward or anterior to the midfoot region 108 and underlies or substantially underlies the ball of the runner’s foot, particularly the metatarsal bones and/or metatarsophalangeal joints. The toe region 112 is anterior to the forefoot region 110 and underlies or substantially underlies the runner’s phalanges (toes).

The wave cushion 104 is illustrated in FIG. 1 as occupying a portion of the sole construction 102 that underlies a portion of the heel region 106, an entirety of the midfoot region 108, and a portion of the forefoot region 110. In other implementations, the wave cushion 104 may occupy any or all of any of the hindfoot or heel region 106, the midfoot region 108, the forefoot region 110, and the toe region 112, depending on what region of the foot the wave cushion 104 is intended to recover energy from. Further, the wave cushion 104 may laterally span some or substantially the entire width of the sole construction 102. Additionally, more than one wave cushion 104 may be included in a single shoe sole (see e.g., FIG. 3B, discussed below).

The wave cushion 104 is generally comprised of a first foundation layer 120 with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer 122 with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane 124 is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer 120 and the second foundation layer 122 and releases kinetic energy by expanding the first foundation layer 120 away from the second foundation layer 122.

The first engagement surface and the second engagement surface together act as alternating matched pairs of actuators and cavities. Each actuator stretches a portion of the elastic membrane 124 into a cavity when the runner’s weight is applied to a top side (e.g., a foot-facing side) of the first foundation layer 120, converting the runner’s kinetic energy to potential energy stored in the stretched and deformed elastic membrane 124. As the runner’s weight is removed from the first foundation layer 120, the elastic membrane 124 springs back into a substantially planar orientation, transferring the stored potential energy back to the runner as kinetic energy.

The foundation layers 120, 122 may be constructed of a stiff, lightweight material that is able to substantially hold its form under a projected load caused by the runner’s impact with the ground while running. Suitable material choices for the foundation layers 120, 122 include without limitation EVA, rubbers (natural or synthetic), thermoplastic polyurethanes (TPU), and thermoplastic elastomers (TPE), any of which may be of a solid or foam construction. Further, the foundation layers 120, 122 can be made of lightweight materials, such as various foams, and then “skinned” with stiffer, but potentially heavier or more expensive materials such as carbon fiber, solid TPU, solid TPE, etc. The elastic membrane 124 may be constructed of any resiliently elastic material that is able to withstand numerous cycles caused by thousands of periodic contacts with the ground over the life of the shoe 100. Suitable material choices for the elastic membrane 124 include without limitation rubbers (natural or synthetic), elastomers, and thermoplastic elastomers (e.g., PEBAX™, Hytrel™, etc.).

The wave cushion 104 may have a substantially even (i.e., non-variable) thickness, or a variable thickness. The thickness of the wave cushion 104 may range, for example, from between about 2 and about 10 centimeters. In implementations where the thickness of the wave cushion 104 is variable along its length and/or width provide stiffer or firmer support or different levels of energy return under different regions of the runner’s foot.

FIG. 2 illustrates an example sole construction 202 including a wave cushion 204 under a progressively increasing compressive load. The sole construction 202 is generally attached to an upper (not shown, see e.g., upper 114 of FIG. 1 ) to form a shoe (not shown, see e.g., shoe 100 of FIG. 1 ). The sole construction 202 includes a cushioning and support layer 216 (also referred to herein as a midsole) including an upper surface (e.g., a foot-facing surface) that is sized and shaped to receive and substantially underlie the runner’s foot, thereby cushioning and supporting the runner’s foot. The cushioning and support layer 216 further includes a lower surface (e.g., a ground-facing surface) that is attached to a wave cushion 204. An abrasive-resistant underlayer 218 is attached to an opposite side of the wave cushion 204 and is configured to contact ground 226 when the shoe is in use. Other implementations may omit one or more layers or include layers in addition to or in lieu of the abrasive-resistant underlayer 218, the cushioning and support layer 216, and the wave cushion 204, and the various sublayers thereof.

The wave cushion 204 is generally comprised of a first foundation layer 220 with a first engagement surface 228 having a first sinusoidal sectional profile and a second foundation layer 222 with a second engagement surface 230 having a second sinusoidal sectional profile. The second engagement surface 230 faces the first engagement surface 228 and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane 224 is oriented between the first engagement surface 228 and the second engagement surface 230 that stores potential energy when compressed between the first foundation layer 220 and the second foundation layer 222 and releases kinetic energy by expanding the first foundation layer 220 away from the second foundation layer 222, as described in further detail below.

The first engagement surface 228 and the second engagement surface 230 together act as alternating matched pairs of actuators and cavities. Each actuator stretches a portion of the elastic membrane 224 into a cavity when the runner’s weight is applied to a top side (e.g., a foot-facing side) of the first foundation layer 220, converting the runner’s kinetic energy to potential energy stored in the stretched and deformed elastic membrane 224. A Load “F” may be conceptualized as all, or a portion of the runner’s weight applied to the sole construction 202.

A progressively increasing load “F” (e.g., No Load, followed by Load F, followed by Load 2F, followed by Load 3F, and followed by Load 4F) is applied to the first foundation layer 220, thereby compressing the first foundation layer 220 into the second foundation layer 222 with the elastic membrane 224 increasingly deformed therebetween. In this example, application of the runner’s full weight is illustrated by Load 4F (the fully compressed state in Step 5), just prior to the runner lifting off for another step.

As the runner’s weight is removed from the first foundation layer 220, the elastic membrane 224 springs back into a substantially planar orientation, transferring the stored potential energy back to the runner as kinetic energy. This is illustrated in FIG. 2 by a progressively decreasing load “F” (e.g., Load 4F, followed by Load 3F, followed by Load 2F, followed by Load F, and followed by No Load) is applied to the first foundation layer 220, thereby permitting the elastic membrane 224 to expand the first foundation layer 220 away from the second foundation layer 222 and add a portion of the runner’s energy utilized to compress the wave cushion 204 back to the runner. In various implementations, greater than 25%, 50%, or 75% of the impact energy is elastically returned to the runner. In implementations where a load greater than 4F is applied to the wave cushion 204, the cushioning and support layer 216, the first foundation layer 220, the second foundation layer 222, and/or other layers of the shoe may densify to absorb more energy and return to their substantially original positions when the additional force is removed from the shoe.

Placing the elastic membrane 224 between the foundation layers 220, 222 and fixing the elastic membrane 224 to one or both of the foundation layers 220, 222 on at least two distal ends, the wave cushion 204 is ready to be “activated.” Applying downward pressure to the first foundation layer 220 causes the elastic membrane 224 to begin stretching and storing energy (as illustrated by a progressively increasing load applied over a period of time). Releasing the pressure will cause the elastic membrane 224 to return to its original substantially planar orientation (as illustrated by a progressively decreasing load applied over a period of time).

The frequency and amplitude of the wave surfaces of the first engagement surface 228 and the second engagement surface 230, along with the thickness and elasticity of the elastic membrane 224 will define how much the elastic membrane 224 will stretch and how much energy may be stored therein. More stretch means greater energy storage and a greater resulting ‘snap-back’ release of energy back to the runner. Less stretch means less energy storage and a lesser resulting ‘snap-back’ release of energy back to the runner. The frequency and amplitude of the wave surfaces of the first engagement surface 228 and the second engagement surface 230, along with the elastic membrane 224 thickness and elasticity, are therefore variables to be selected when ‘tuning’ the wave cushion 204 to provide a desired ‘snap-back.’

FIG. 3A illustrates an example shoe 300 having a sole construction 302 including a full-length wave cushion 304. The wave cushion 304 illustrated in FIG. 3A occupies a portion of the sole construction 302 that underlies a portion of heel region 306, an entirety of midfoot region 308, and a portion of forefoot region 310 of the shoe 300. In other implementations, the wave cushion 304 may occupy any or all of any of the hindfoot or heel region 306, the midfoot region 308, the forefoot region 310, and toe region 312, depending on what region of the foot the wave cushion 304 is intended to recover energy from.

Additionally, more than one wave cushion may be included in a single shoe sole (referred to herein as localized wave cushions). For example, FIG. 3B illustrates an example shoe 301 having a sole construction 303 including localized wave cushions 305, 307. The wave cushion 305 occupies a portion of the sole construction 303 that underlies a portion of the heel region 306, while the wave cushion 307 occupies a portion of the sole construction 303 that underlies a portion of the forefoot region 310 of the shoe 301. Further, the wave cushions 304, 305, 307 may laterally span some or substantially the entire width of the sole constructions 302, 303.

FIGS. 4A-4C illustrate example wave cushions 404, 405, 407, respectively, with varying frequencies and amplitudes. The wave cushions 404, 405, 407 are each generally comprised of a first foundation layer 420 with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer 422 with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane 424 is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer 420 and the second foundation layer 422 and releases kinetic energy by expanding the first foundation layer 420 away from the second foundation layer 422.

The first engagement surface and the second engagement surface together act as alternating matched pairs of actuators and cavities. Each actuator stretches a portion of the elastic membrane 424 into a cavity when the runner’s weight is applied to a top side (e.g., a foot-facing side) of the first foundation layer 420, converting the runner’s kinetic energy to potential energy stored in the stretched and deformed elastic membrane 424. As the runner’s weight is removed from the first foundation layer 420, the elastic membrane 424 springs back into a substantially planar orientation, transferring the stored potential energy back to the runner as kinetic energy.

Frequency and amplitude of the wave cushion 404, 405, 407 generally refers to oscillation of the surface of the foundation layers 420, 422 facing the elastic membrane 424. The “Low Frequency, Low Amplitude” implementation of the wave cushion 404 is generally capable of storing less energy than the “High Frequency, Low Amplitude” implementation of the wave cushion 405 and the “High Frequency, High Amplitude” implementation of the wave cushion 407, assuming the wave cushions 404, 405, 407 are constructed of identical materials and overall dimensions.

The “High Frequency, Low Amplitude” implementation of wave cushion 405 may achieve a greater number of matched pairs of actuators and cavities than the wave cushion 404, and thus the greater capacity for storing energy in the stretched and deformed elastic membrane 424. The “High Frequency, High Amplitude” implementation of wave cushion 407 is able to achieve a greater stroke than the wave cushions 404, 405 and thus the greater capacity for storing energy in the stretched and deformed elastic membrane 424. In sum, the wave cushions 404, 405, 407 can be “tuned” by altering the amplitude and/or frequency of the waves formed by the foundation layers 420, 422. As a result, an associated shoe may be specifically tuned for a user, not only by their foot size and shape, but the user’s body weight and intended purpose for the shoe (running vs. jogging vs. walking, and for various sports, athletic, or work activities).

FIGS. 5A and 5B illustrate flexure of an example wave cushion 500, 505. The wave cushion 500, 505 is generally comprised of a first foundation layer 520 with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer 522 with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane 524 is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer 520 and the second foundation layer 522 and releases kinetic energy by expanding the first foundation layer 520 away from the second foundation layer 522.

The cushion 500, 505 is illustrated in FIG. 5A in a flexed state and FIG. 5B in an unflexed state. Flexure of the cushion 500, 505 is aided by the orientation of the sinusoidal sectional profile. Specifically, the cushion 500, 505 is more flexible in the direction of the sinusoidal sectional profiles of the engagement surfaces, as depicted, and less flexible transverse to the direction of the sinusoidal sectional profiles (in a direction normal to the view of FIGS. 5A and 5B). As a result, the cushion 500 can be oriented within a shoe to aid flexure in an intended direction (e.g., anterior to posterior in the implementation of FIGS. 5A and 5B).

FIG. 6A illustrates a perspective view of an example foundation layer 620 of a wave cushion with an engagement surface wave profile running exclusively in the y-direction. This is referred to herein as a two-dimensional or 2D foundation layer 620 for use in a two-dimensional or 2D wave cushion (see e.g., wave cushion 904 of FIG. 9 ). In various implementations, the 2D foundation layer 620 is comparable to the foundation layer 120 of FIG. 1 and has features as described above. Further, the 2D foundation layer 620 may be oriented within a shoe with the engagement surface wave profile running in an anterior to posterior direction. This orientation permits more flexure of the shoe longitudinally in an anterior to posterior direction (as illustrated by flexed state 500 of FIG. 5A) than laterally in a medial to lateral direction. In other implementations, the 2D foundation layer 620 may be oriented within a shoe with the engagement surface wave profile running in the medial to lateral direction to permit more flexure of the shoe laterally in the medial to lateral direction than longitudinally in the anterior to posterior direction.

FIG. 6B illustrates a perspective view of an example foundation layer 621 wave cushion with an engagement surface wave profile running in both the x-direction and the y-direction. This is referred to herein as a three-dimensional or 3D foundation layer 621 for use in a three-dimensional or 3D wave cushion. In various implementations, the 3D foundation layer 621 is also comparable to the foundation layer 120 of FIG. 1 and has features as described above. While the 2D foundation layer 620 of FIG. 6A encourages bending in the x-direction over the y-direction, the 3D foundation layer 621 has no similar bending direction. Thus, orientation of the engagement surface wave profile of the 3D foundation layer 621 within a shoe may not substantially affect the shoe’s flexure. This may permit a more flexible placement of the 3D foundation layer 621 within the shoe. Each of the foundation layers 620, 621 are intended to be assembled with a matching foundation layer with a half-period phase offset, as well as an elastic membrane (not shown, see e.g., elastic membrane 124 of FIG. 1 ) secured therebetween.

If the wave profile runs in a singular direction, as with the 2D foundation layer 620 of FIG. 6A, a locking arrangement that secures opposing sides or ends 605, 610 of the 2D foundation layer 620 to an associated elastic membrane may be used because the stretching forces are running longitudinally or in the y-direction. If the wave profile runs in both in the x-direction and the y-direction, as with the 3D foundation layer 621 of FIG. 6B, a locking arrangement that secures all sides 615, 625, 630, 635 of the 3D foundation layer 621 to an associated elastic membrane may be used because the stretching forces are not just running longitudinally, but also side-to-side. In further implementations, the locking arrangement that secures all sides may also be used to further secure a 2D foundation layer, such as 2D foundation layer 620.

Further, as compared to the 2D foundation layer 620 of FIG. 6A, the ‘xy’ wave configuration of 3D foundation layer 621 of FIG. 6B may stretch more of the elastic membrane, and therefore apply more tension to the elastic membrane than an x-direction or y-direction only wave. Energy storage may be doubled since the elastic membrane is stretched in two directions instead of only one. The variation between foundation layers 620, 621 affects the energy storage capacity of the corresponding elastic membrane.

FIGS. 7A-7C illustrate example wave cushions 704, 705, 707 with varying locking arrangements or features. The wave cushion 704 is generally comprised of a first foundation layer 720 with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer 722 with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane 724 is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer 720 and the second foundation layer 722 and releases kinetic energy by expanding the first foundation layer 720 away from the second foundation layer 722.

The wave cushion 704 is illustrated with a “Belt” locking arrangement, which applies T-shaped ends on the elastic membrane 724 that engage with the foundation layers 720, 722 so that the elastic membrane 724 is forced to stretch rather than slip between the foundation layers 720, 722 under load. In a 2D implementation, with 2D foundation layers such as 2D foundation layer 620 of FIG. 6A, the T-shaped ends on the elastic membrane 724 may be applied only at the opposing sides of the foundation layers 720, 722 (see e.g., opposing sides 605, 610 of the 2D foundation layer 620). In a 3D implementation, with 3D foundation layers such as 3D foundation layer 621 of FIG. 6B, the T-shaped ends on the elastic membrane 724 may be applied around all sides of the foundation layers 720, 722 (see e.g., sides 615, 625, 630, 635 of the 3D foundation layer 621).

The wave cushion 705 is generally comprised of a first foundation layer 721 with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer 725 with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane 726 is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer 721 and the second foundation layer 725 and releases kinetic energy by expanding the first foundation layer 721 away from the second foundation layer 725.

The wave cushion 705 is illustrated with a “Single Box” locking arrangement, which applies L-shaped ends on the elastic membrane 726 that engage with the foundation layer 721 exclusively (or in other implementations, the foundation layer 725 exclusively) so that the elastic membrane 726 is similarly forced to stretch rather than slip between the foundation layers 721, 725 under load. As compared to the “Belt” locking arrangement of FIG. 7A, in the “Single Box” locking arrangement of FIG. 7B, it is sufficient to hold the ends of the elastic membrane 726 to the foundation layer 721 exclusively. This may yield the L-shaped ends on the elastic membrane 726 extending further than the T-shaped ends on the elastic membrane 724, as illustrated.

The wave cushion 707 is generally comprised of a first foundation layer 723 with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer 727 with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π). An elastic membrane 728 is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer 723 and the second foundation layer 727 and releases kinetic energy by expanding the first foundation layer 723 away from the second foundation layer 727.

Wave cushion 707 is illustrated with a “Double Box” locking arrangement, which applies L-shaped ends on the elastic membrane 728 so that the elastic membrane 728 is forced to stretch rather than slip between the foundation layers 723, 727 under load. While the elastic membrane 728 of the wave cushion 707 is similar to the elastic membrane 726 of the wave cushion 705, the foundation layer 727 of the “Double Box” locking arrangement includes boxed ends that extend vertically and further secure the foundation layer 727 with reference to the foundation layer 723 and the elastic membrane 728, and also provide further touchpoints at the ends (or endpoints) of the elastic membrane 728 to potentially attach to the foundation layer 727.

In various implementations, glue, cement, or welding at one or more endpoints (e.g., endpoints 741, 742, 743) or touchpoints (e.g., touchpoints 731, 732, 733) between the elastic membranes 724, 726, 728 and their respective foundation layers adheres the elastic membranes 724, 726, 728 to their respective foundation layers and thus aids in keeping the cushions 704, 705, 707 together and the elastic membranes 724, 726, 728 in place, respectively. In implementations where the elastic membranes 724, 726, 728 are only secured at their respective ends or sides, an entirely of the elastic membranes 724, 726, 728 may be used for energy storage when compressed. In implementations where the elastic membranes 724, 726, 728 are further secured at touchpoints with their respective foundation layers, nearly all the elastic membranes 724, 726, 728 may be used for energy storage when compressed, with exceptions only at areas of attachment to their respective foundation layers.

The “Belt”, “Single Box”, and “Double Box” locking arrangements serve at least four purposes. First, the vertical aspect of the locking arrangement forms full or partial ‘box walls’ around the elastic membranes 724, 726, 728. This allows tension to be applied to the elastic membranes 724, 726, 728 and maintained so the elastic membranes 724, 726, 728 will not slip between when their respective foundation layers stretch the elastic membranes 724, 726, 728 under compression. Second, the vertical aspects of the locking arrangements keep the individual elements of the foundation layers ‘in line’ as they travel up and down. Third, the vertical aspects of the locking arrangements protect the foundation layers from interference from a surrounding midsole. Further, the vertical aspects of the locking arrangements are positioned below the top of the foundation layers 720, 721, 723 and above the bottom of the foundation layers 722, 725, 727 to avoid interference. Otherwise, the vertical aspects of the locking arrangements may restrict the travel of the wave cushions 704, 705, 707. Fourth, the “Double Box” locking arrangement may form an enclosed “cassette” format for the wave cushion 707.

FIG. 8 illustrates an example wave cushion 804 configured as a pre-assembled cassette to be installed into a sole construction cavity or aperture 832. Sole construction 802 is generally attached to an upper (not shown, see e.g., upper 114 of FIG. 1 ) to form an overall shoe (not shown, see e.g., shoe 100 of FIG. 1 ). The sole construction 802 includes a cushioning and support layer 816 (also referred to herein as a midsole) including an upper surface (e.g., a foot-facing surface) that is sized and shaped to receive and substantially underlie the runner’s foot, thereby cushioning and supporting the runner’s foot. The cushioning and support layer 816 further includes a lower surface (e.g., a ground-facing surface) including a cavity 832 that receives a wave cushion 804. An abrasive-resistant underlayer 818 is attached to an opposite side of the wave cushion 804 and the cushioning and support layer 816 and is configured to contact ground when the shoe is in use. Other implementations may omit one or more layers or include layers in addition to or in lieu of the abrasive-resistant underlayer 818, the cushioning and support layer 816, and the wave cushion 804, and the various sublayers thereof.

The wave cushion 804 takes the form of a pre-assembled cassette that can be permanently placed and secured within the aperture 832 at a time of manufacture. Alternatively, the wave cushion 804 may be removable (e.g., the wave cushion 804 may be removably placed with the aperture 832 so that it may be replaced periodically, in some implementations by an end-user (e.g., a runner)). In various implementations, the aperture 832 may be access from a bottom side of the cushioning and support layer 816, as illustrated, or a top side of the cushioning and support layer 816. Further, the pre-assembled cassette may preload the wave cushion 804 by partially deforming (or pre-tensioning) the elastic membrane 824 between foundation layers 820, 822 in a resting state. This ensures that the wave cushion 804 responds immediately and consistently to loading during use.

FIG. 9 illustrates a sectional view of another example sole construction 902 including a wave cushion 904. While the sole construction 902 is depicted as rectangular, it is a partial sectioned view only so for illustration purposes. For example, the sole construction 902 may be sized and shaped to correspond to all or a portion of a user’s foot. The sole construction 902 is generally attached to an upper (not shown, see e.g., upper 104 of FIG. 1 ) to form an overall shoe (not shown, see e.g., shoe 100 of FIG. 1 ).

The wave cushion 904 is generally comprised of a first foundation layer 920 with a first engagement surface 928 having a first sinusoidal sectional profile and a second foundation layer 922 with a second engagement surface 930 having a second sinusoidal sectional profile. The second engagement surface 930 faces the first engagement surface 928 and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π).An elastic membrane 924 is oriented between the first engagement surface 928 and the second engagement surface 930 that stores potential energy when compressed between the first foundation layer 920 and the second foundation layer 922 and releases kinetic energy by expanding the first foundation layer 920 away from the second foundation layer 922, as described in further detail above. The wave cushion 904 may be configured as a cassette that is removable from an aperture or cavity in a cushioning and support layer 916 in the shoe.

In some implementations, the first foundation layer 920 stands proud of the surrounding elastic membrane 924 and cushioning and support layer 916 on a top side of the wave cushion 904 and therefore can act as a top-down plunger for the wave cushion 1004. Acting as a plunger, the first foundation layer 920 serves to distribute applied force from the user’s foot on the wave cushion 904. Further, an abrasive-resistant underlayer 918 is attached to an opposite side of the wave cushion 904 and is configured to contact ground when the shoe is in use. In some implementations, ground-engaging lugs (e.g., lug 919) protruding from a bottom side of the wave cushion 904 stand proud of surrounding lugs within the abrasive-resistant underlayer 918, as shown. As a result, the abrasive-resistant underlayer 918 can therefore act as a bottom-up plunger for the wave cushion 904. Other implementations may omit one or more layers or include layers in addition to or in lieu of the abrasive-resistant underlayer 918, the cushioning and support layer 916, the wave cushion 904, and the various sublayers thereof.

The elastic membrane 924 includes outwardly extending flanges 990, 992 that provide attachment surfaces for securing the sole construction 902 when it is nested into a recess in a footbed of a shoe. In various implementations, the flanges 990, 992 may take the form of multiple discontinuous flanges or a singular continuous flange running about all or a period of a perimeter of the wave cushion 904. The wave cushion 904 may be placed within the aperture accessible from a top side or a bottom side of the footbed and the flanges 990, 992 may aid in locking the elastic membrane 924 in place. For example, the wave cushion 904 may be placed within the aperture from the top and the flanges 990, 992 may be secured to the cushioning and support layer (not shown, see e.g., cushioning and support layer 106 of FIG. 1 ) and suspend the wave cushion 904 within the aperture. Further, the flanges 990, 992 may permit the elastic membrane 924 to be locked in place in a pre-tensioned condition.

FIG. 10 illustrates a perspective view of another example sole construction 1002 including a wave cushion 1004. While the sole construction 1002 is depicted as rectangular, it is a partial sectioned view only so for illustration purposes. For example, the sole construction 1002 may be sized and shaped to correspond to all or a portion of a user’s foot. The sole construction 1002 is generally attached to an upper (not shown, see e.g., upper 104 of FIG. 1 ) to form an overall shoe (not shown, see e.g., shoe 100 of FIG. 1 ).

The sole construction 1002 includes a plunger 1016 (e.g., a firm block of foam) that may be oriented between a midsole (not shown) and the wave cushion 1004. The plunger 1016 serves to distribute applied force from the user’s foot on the wave cushion 1004. Further, an abrasive-resistant underlayer 1018 is attached to an opposite side of the wave cushion 1004 and is configured to contact ground 1026 when the shoe is in use. Other implementations may omit one or more layers or include layers in addition to or in lieu of the abrasive-resistant underlayer 1018, the plunger 1016, and the wave cushion 1004, and the various sublayers thereof.

The wave cushion 1004 is generally comprised of a first foundation layer 1020 with a first engagement surface 1028 having a first sinusoidal sectional profile and a second foundation layer 1022 with a second engagement surface 1030 having a second sinusoidal sectional profile. The second engagement surface 1030 faces the first engagement surface 1028 and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π).An elastic membrane 1024 is oriented between the first engagement surface 1028 and the second engagement surface 1030 that stores potential energy when compressed between the first foundation layer 1020 and the second foundation layer 1022 and releases kinetic energy by expanding the first foundation layer 1020 away from the second foundation layer 1022, as described in further detail above. The wave cushion 1004 may be configured as a cassette that is removable from an aperture or cavity in a cushioning and support layer in the shoe, as shown and described above with reference to FIG. 8 .

The elastic membrane 1024 includes outwardly extending flanges 1090, 1092 that provide attachment surfaces for securing the sole construction 1002 when it is nested into a recess in a footbed of a shoe. In various implementations, the flanges 1090, 1092 may take the form of multiple discontinuous flanges or a singular continuous flange running about all or a period of a perimeter of the wave cushion 1004. The wave cushion 1004 may be placed within the aperture accessible from a top side or a bottom side of the footbed and the flanges 1090, 1092 may aid in locking the elastic membrane 1024 in place. For example, the wave cushion 1004 may be placed within the aperture from the top and the flanges 1090, 1092 may be secured to the cushioning and support layer (not shown, see e.g., cushioning and support layer 106 of FIG. 1 ) and suspend the wave cushion 1004 within the aperture. Further, the flanges 1090, 1092 may permit the elastic membrane 1024 to be locked in place in a pre-tensioned condition.

In some implementations, one of the foundation layers 1020, 1022 may have a deeper sinusoidal sectional profile than the other, which may permit additional travel of the wave cushion 1004. Still further, the wave cushion 1004 has a larger overall vertical travel as compared to wave cushion 104 of FIG. 1 , for example, and may thus be optimized for the greater per unit area loading typical of heel cushioning as compared to mid-foot or forefoot cushioning.

FIG. 11 illustrates example operations 1100 for providing elastic energy return to a user during an impact event with a ground surface. A providing operation 1105 provides a cushioning and support layer in a shoe sole to cushion a user’s foot during the impact event. The cushioning and support layer is made of a soft, pliable material. In one implementation, the cushioning and support layer spans substantially the entire length of the user’s foot, both medial to lateral and posterior to anterior. The cushioning and support layer may include an upper surface (e.g., a foot-facing surface) that is sized and shaped to receive and substantially underlie the user’s foot.

A second providing operation 1110 provides a wave cushion between the cushioning and support layer and the ground to receive energy from the impact event and release the stored energy back to the user’s foot to assist the user’s next stride. The wave cushion includes a first foundation layer with a first engagement surface having a first sinusoidal sectional profile and a second foundation layer with a second engagement surface having a second sinusoidal sectional profile. The second engagement surface faces the first engagement surface, and the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π).An elastic membrane is oriented between the first engagement surface and the second engagement surface that stores potential energy when compressed between the first foundation layer and the second foundation layer and releases kinetic energy by expanding the first foundation layer away from the second foundation layer.

A compression operation 1115 compresses the wave cushion under the user’s foot when the user’s foot impacts the ground surface in an impact event. The elastic membrane within the wave cushion stretches to absorb energy from the impact event in a form of potential energy. A de-compression operation 1120 de-compresses the wave cushion when the user’s foot leaves the ground surface to return a portion of the applied energy to the user’s stride in a form of kinetic energy. The compression operation and de-compression operations 1115, 1120 are repeated each time each of the user’s feet impacts on and rebounds from the ground surface to help propel the user forward in a running, jogging, or walking stride.

The foregoing logical method steps making up implementations of the invention may be referred to variously as operations or steps. Further, the logical method steps may be performed in any order, adding or omitting as desired, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.

Various figures herein depict partial and/or sectional views of sole constructions, wave cushions, and components thereof. This should not be viewed as requiring the depicted sizes and shapes of the wave cushions and components thereof. For example, the sole constructions, wave cushions, and components thereof may be sized and shaped to correspond to all or a portion of a user’s foot. Substantially planar, substantially sinusoidal, and other shapes and dimensions as used herein refers to described structures conforming to the described shapes within industry-standard manufacturing tolerances. The above specification, examples, and drawings provide a complete description of the structure and use of exemplary implementations of the invention. Since many implementations of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. Furthermore, structural features of the different implementations may be combined in yet another implementation without departing from the recited claims. 

What is claimed is:
 1. A sole construction for a shoe comprising: a first foundation layer with a first engagement surface having a first sinusoidal sectional profile; a second foundation layer with a second engagement surface having a second sinusoidal sectional profile, the second engagement surface facing the first engagement surface, wherein the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π); and an elastic membrane oriented between the first engagement surface and the second engagement surface, wherein the elastic membrane is to store potential energy when compressed between the first foundation layer and the second foundation layer, and wherein the elastic membrane is to release kinetic energy when permitted to expand the first foundation layer away from the second foundation layer.
 2. The sole construction of claim 1, wherein the first foundation layer, the second foundation layer, and the elastic membrane in combination form a wave cushion, wherein the sole construction further comprises: a cushioning and support layer, wherein the wave cushion is oriented within an aperture in the cushioning and support layer.
 3. The sole construction of claim 2, further comprising: a ground engagement layer applied over a lower surface of the cushioning and support layer.
 4. The sole construction of claim 2, wherein the wave cushion underlies one or more of a heel region, a midfoot region, a forefoot region, and a toe region of the shoe.
 5. The sole construction of claim 2, wherein the wave cushion is a cassette removable from the aperture in the cushioning and support layer.
 6. The sole construction of claim 5, wherein the aperture is accessed from a top side of the cushioning and support layer.
 7. The sole construction of claim 6, wherein the elastic membrane includes an outwardly extended flange that is secured to the cushioning and support layer and suspends the wave cushion within the aperture.
 8. The sole construction of claim 1, wherein the foundation layers are three-dimensional.
 9. The sole construction of claim 1, wherein the foundation layers are two-dimensional and oriented with the sinusoidal sectional profiles running anterior to posterior.
 10. The sole construction of claim 1, wherein the foundation layers are two-dimensional and oriented with the first and the second sinusoidal sectional profiles running medial to lateral.
 11. The sole construction of claim 1, wherein one of the foundation layers includes ground-engaging features.
 12. The sole construction of claim 1, wherein the elastic membrane is pretentioned between the foundation layers.
 13. The sole construction of claim 1, wherein a majority of the elastic membrane is stretched and deformed to store the potential energy therein.
 14. The sole construction of claim 1, wherein the elastic membrane includes a locking feature at its ends secured to one or both of the first foundation layer and the second foundation layer.
 15. The sole construction of claim 14, wherein the locking feature includes T-shaped or L-shaped ends of the elastic membrane.
 16. The sole construction of claim 14, wherein the locking feature includes vertical ends of the second foundation layer.
 17. The sole construction of claim 1, wherein the elastic membrane is adhered to touchpoints with one or both of the first foundation layer and the second foundation layer.
 18. The sole construction of claim 1, wherein the elastic membrane is adhered to endpoints with one or both of the first foundation layer and the second foundation layer.
 19. A method of providing elastic energy return comprising: providing a sole construction including: a first foundation layer with a first engagement surface having a first sinusoidal sectional profile; a second foundation layer with a second engagement surface having a second sinusoidal sectional profile, the second engagement surface facing the first engagement surface, wherein the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π); and an elastic membrane oriented between the first engagement surface and the second engagement surface; storing potential energy within the elastic membrane when compressed between the first foundation layer and the second foundation layer; and releasing kinetic energy from the elastic membrane when it is permitted to expand the first foundation layer away from the second foundation layer.
 20. A shoe comprising: a wave cushion including: a first foundation layer with a first engagement surface having a first sinusoidal sectional profile; a second foundation layer with a second engagement surface having a second sinusoidal sectional profile, the second engagement surface facing the first engagement surface, wherein the second sinusoidal sectional profile is phase offset from the first sinusoidal sectional profile by a half of a period (π); an elastic membrane oriented between the first engagement surface and the second engagement surface, wherein the elastic membrane is to store potential energy when compressed between the first foundation layer and the second foundation layer, and wherein the elastic membrane is to release kinetic energy when permitted to expand the first foundation layer away from the second foundation layer; a cushioning and support layer, wherein the wave cushion is oriented within an aperture in the cushioning and support layer; an upper to surround and enclose a user’s foot, wherein the upper is attached to an upper surface of the cushioning and support layer; and a ground engagement layer applied over a lower surface of the cushioning and support layer. 